Closer to home on August 30, two of the bombers were seen flying over the White Cliffs of Dover alongside two RAF F-35 jets.

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General Jeff Harrigian, commander of US Air Forces in Europe and Air Forces Africa, said: "Bomber Task Force missions provide us an opportunity to train and integrate with our allies and partners in the region.

"When we bring bombers like the B-2 into theatre, they deliver a measure of deterrence and enhance our ability to develop our overall readiness, our posture and further increase our partnerships across the globe."

First built as a prototype nuclear bomber in 1987, the Northrop Grumman B-2 Spirit - to give its full name - it earned the nickname "stealth bomber" thanks to being able to remain undetected by sophisticated anti-aircraft defence systems.

It is estimated that each unit costs a whopping $2.1billion, with 21 of the distinctive aircraft being built since their introduction to military service in 1997.

Today, 20 remain in service although they are planned to retire in 2032.